1. Field of the Invention
This invention relates to a photographic silver-halide emulsion. More particularly, this invention relates to a sensitizing agent for use in a photographic silver-halide emulsion which improves the sensitivity of the photographic halide emulsion while decreasing intensity of the same to develop a veil or fog following sensitization or during storage.
2. Discussion of the Prior Art
It is known, in order to improve the chemical development of a photographic film or plate, to add to the photographic emulsion a sulfur containing sensitizer such as, for example, a symmetrical disulfide, a cysteine, a cystine or an N-substitive product thereof. Reduction agents or gold compounds or combinations thereof have also been used as sensitizers. The use of these materials increases the sensitivity of the photographic emulsion during the digestion or ripening process. However, for many purposes, the attained sensitivity increase is inadequate or is afflicted with the disadvantage of a strong tendency toward fogging. The resultant veil or fog form can sometimes occur only following the spectral sensitization or during storage.
It has therefore become desirable to provide a photographic silver-halide emulsion which possessess a high sensitivity. More specially, it has become desirable to provide such a photographic silver-halide emulsion which has a marked reduced tendency toward fog formation. Accordingly, it is an object of the present invention to provide an improved photographic silver-halide emulsion characterized by high sensitivity and reduced tendency to fog formation. It is a special object of the present invention to provide a photographic emulsion having increased sensitivity and gradation.